Cam-driven linear actuator apparatus

Abstract

A precision, high load capacity linear actuator apparatus incorporating a rotary-actuated cam is disclosed. A moveable load carriage assembly containing a cam member mounted on bearings therein is free to ride linearly on stationary tracks. The cam member engages stationary cam followers mounted on the stationary tracks' support. In the preferred embodiment, a linear ball-slide mechanism supported in bearings at each end of the stationary track passes through the cam member, with its linear slide member attached to the cam's center bore. Rotary actuation of the linear ball-slide shaft causes rotation of the cam member which is converted into a linear motion of the load carriage along the stationary track. Thus, linear positioning of the load carriage is effected through rotary positioning of the ball-slide shaft through associated motor means. In an alternate embodiment, to be utilized where extremely long linear strokes are required, the drive motor assembly is mounted directly to and travels with the moveable load carriage assembly so as to directly drive the cam member.

I claim: 
     
       1. A linear actuator apparatus comprising: a drive motor assembly;   slide mechanism means driven by said drive motor assembly and operable to convert rotary motion into linear motion, said slide mechanism means comprising an elongated shaft means and a slide means, said slide means rotatably driven by said shaft means and linearly slidable therealong;   a drive cam member securably mounted to said slide means and operable to both rotate and linearly slide therewith;   a plurality of aligned cam follower members each positionally fixed and respectively engageable with said drive cam member; and   load carriage means journalled for sliding movement along a path parallel to said plurality of aligned cam follower members, said load carriage means also journalably supported relative to said drive cam member and said slide means, whereby rotation of said drive motor causes rotation of said drive cam member whereupon said engagement of said positionally fixed cam follower members with said drive cam member causes said drive cam member and said load carriage means to move linearly.   
     
     
       2. The invention of claim 1, wherein said slide mechanism means comprises ball slide means in which said elongated shaft means comprises an elongated drive shaft having axially-protruding drive ribs and said slide means comprises a ball slide spline nut carrying a recirculating series of drive balls engageable with said drive ribs. 
     
     
       3. The invention of claim 2, wherein said drive ribs extend longitudinally of said elongated drive shaft. 
     
     
       4. The invention of claim 1, wherein said load carriage means is journalled directly on said drive cam member. 
     
     
       5. A linear actuator apparatus comprising: load carriage means linearly slidably supported by elongated track means;   drive cam means rotatably supported relative to said load carriage means;   a plurality of cam follower means positionally fixed in a series aligned parallel with said elongated track means and each respectively engageable with said drive cam means, said cam follower means being pre-loaded with said drive cam means so as to prevent backlash therebetween; and   drive motor assembly means mounted to said load carriage means and directly rotatably driving said drive cam means, whereby rotation of said drive cam means against said positionally fixed cam follower means effects controlled linear sliding movement of said drive cam means and said load carriage means along said elongated track means.